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Northfield Roundabout Transformation

Challenge

The TH 246 and Jefferson Parkway intersection in the City of Northfield was previously a four-way stop faced with heavy traffic, increased public frustration and unsafe conditions for pedestrians and motorized traffic. The City sought a multimodal solution to improve traffic efficiency and safety, and provide access for students making their way to school.

In partnership with SEH, the City evaluated intersection alternatives, coordinated with multiple stakeholders and funding mechanisms (e.g., Minnesota Department of Transportation [MnDOT], local businesses, Northfield School District, Local Road Improvement Program, Municipal State Aid funds and City Enterprise Funds) and undertook extensive public outreach and education.

After careful study and consideration, the project team determined a roundabout would be the best-fit solution to transform this four-way stop into a multimodal City connection point. The SEH team’s design also incorporated four underpass tunnels to provide safe routes for pedestrians and bicyclists – a necessity given the proximity to local schools and a future regional trail route.

Solution

The City trusted SEH with a wide range of services, including planning, permitting, right-of-way, traffic analyses, roadway engineering and construction administration.

The SEH team initially conducted an intersection control evaluation (ICE) and traffic impact analysis (TIA) to evaluate the intersection and explore viable alternatives. Prioritizing the City’s Safe Routes to School Plan, the team assessed multiple options before deciding on a roundabout. This solution would alleviate lengthy peak-hour backups and delays, provide pedestrian and bicycle access, improve access to nearby schools, and enhance safety for all users.

Through a feasibility study, SEH developed and analyzed four roundabout alternatives for City officials and the public to consider as they moved the project forward.

Public outreach elevates community buy-in
The Northfield community was supportive of this highly visible project because of the need to improve safety near the schools and the ongoing frustrations with delays during peak hours. To maintain and nurture this support, the City and SEH engaged the community in a way that would allow all stakeholders to understand, rate and review four roundabout alternatives.

The project team presented at a City Council workshop, open house and public hearing, and held a Q&A session at all events. In addition, they shared comment cards and provided a public input “coloring book” to open house attendees. The coloring books allowed people to mark up the intersection with ideas and leave comments on the four alternatives they preferred.

Beyond the open house, public hearing and workshop, the SEH team utilized a web-based survey – meeting with community members and providing updates on the City website to keep the public engaged and informed.

SEH provided different cost scenarios that included two tunnels compared to the four-tunnel design. The City ultimately selected the four-tunnel option as it offered future opportunities to expand the sidewalk facilities without shutting down the intersection during construction. While the City Council made the final design decision, SEH and the City garnered and maintained support for a complex intersection solution through their engaging outreach process.

Feedback inspires new ideas and solutions
The public outreach effort inspired several unique design solutions:

  • Enhanced intersection treatment, including decorative paving, additional signage and new pedestrian ramps.
  • Landscaping and bold mural art on the culverts from a local artist, further contributing to a sense of place and creating a park-like feel at the grade-separated multimodal crossings.
  • Sidewalk and trails leading up to the roundabout lit with pedestrian lighting.
  • Bike ramps to and from the roadway, allowing pedestrian traffic to exit the roadway prior to the roundabout and to utilize the shared use pathways to navigate the intersection.

Proactive coordination with multiple stakeholders
Designing the roundabout and its four underpass tunnels on a trunk highway required coordination with multiple agencies and various approvals. Design standards needed to adhere to trunk highway standards and ensure agriculture vehicles could also navigate through the roundabout.

The SEH team proactively coordinated with the City and two MnDOT offices – MnDOT District 6 and MnDOT Metro to ensure there were no unnecessary delays and the project was compliant with requirements,.

Open access during construction important for project success
Forward-thinking and true partnership empowered the team to construct the project in one construction season – ensuring it was fully complete by the start of school and keeping the roadway open to traffic. Accomplishing this through:

  • Providing a contractor incentive during the bidding process to have the project completed by a specific date.
  • Working closely with the Northfield Public School District to minimize disturbance to the adjacent school property – including traffic control to help maintain access to an elementary school that had programing for students of essential area staff.
  • Coordinating with Dakota and Rice counties to develop a detour plan, allowing the intersection to be entirely closed for construction.
  • Conducting weekly construction progress meetings throughout the construction process to keep everyone updated on the status or adjustments needed.

Overall, the completed roundabout has provided local schools and residents with improved safety, multimodal access and artistic infrastructure that inspires pride communitywide.

Awards

  • 2022 Engineering Excellence Grand Award | American Council of Engineering Companies, Minnesota Chapter (ACEC-MN)
  • 2022 Honorable Mention Award | City Engineers Association of Minnesota (CEAM)

Project
Trunk Highway (TH) 246 and Jefferson Parkway Reconstruction

Location
Northfield, Minnesota

Client
City of Northfield, Minnesota

Features

  • Project constructed in one season to ensure roadway was open in time for school season.
  • Underpass tunnels provide aesthetically pleasing, safe travel for pedestrians and bicyclists.
  • Roundabout eliminated lengthy peak-hour delays.
  • Lighting along sidewalk, trails and underpass tunnels to enhance safety for all users.
  • Proactive stakeholder engagement achieved buy-in from residents and school system.

Services

  • Civil engineering
  • Highway design
  • Mechanical/electrical engineering
  • Geotechnical engineering
  • Structural engineering
  • Survey
  • Traffic engineering
  • Lighting design
  • Storm sewer design
  • Landscape design
  • Construction administration
  • Public involvement